Polyploidy in Plants MCQs Polyploidy refers to a state of condition where a plant possesses more than two sets of chromosomes. Polyploidy is a key factor in plant evolution and breeding, resulting in the development of new species and varieties with desirable characteristics. This article discusses the phenomenon of polyploidy in plants, its nature, causes, and uses in plant breeding and genetic enhancement. For students of CSS Competitive Exam, the concept of polyploidy is critical for responding to questions about plant genetics, evolutionary biology, and biotechnology.
Types of Polyploidy
Polyploidy in plants is divided into two primary categories: autopolyploidy and allopolyploidy.
Autopolyploidy results when a plant possesses more than one set of chromosomes of the same species. This might be due to cell division errors, causing the repetition of the entire chromosome set. Autopolyploids will usually show the tendency of having larger cells, which can extend to having larger fruits and flowers, and also tend to express higher vigor or hybrid vigor.
Allopolyploidy is the union of two distinct species, which creates a hybrid plant with two sets of chromosomes from each species. Allopolyploidy is more prevalent in nature and plays an important role in the evolution of most plant species. Wheat is a famous example of an allopolyploid since it has chromosomes from several grass species. Allopolyploids tend to be more fertile and tolerant than their diploid (two-set chromosome) relatives.
Causes of Polyploidy in Plants
Polyploidy in plants may result from a variety of mechanisms, the most frequent of which are mitotic or meiotic errors. Doubling of chromosomes can happen when there is an impairment in the segregation of chromosomes during cell division, leading to cells with twice the normal number of chromosomes. Polyploidy can also be caused by environmental factors, like chemicals (e.g., colchicine) or radiation. Also, inter-specific hybridization may result in allopolyploidy, where the hybrid progeny inherits chromosome sets from both the parental species, usually resulting in increased size and vigor.
Applications of Polyploidy in Plant Breeding
Polyploidy is extensively applied in plant breeding due to its ability to produce plants with desirable characteristics like increased size, enhanced disease resistance, and increased yield. Tetraploids (four chromosome sets) tend to be stronger and more adapted to some environmental conditions, so they find application in agriculture. Seedless watermelons, for instance, are usually tetraploid, and larger and more resistant crops tend to be polyploids. Polyploidy is also applied to enhance crop hybrids since it can cause hybrid vigor, where the hybrid plants show improved growth, fertility, and strength compared to the diploid counterparts.
Yet, polyploidy also has its problems, including possible sterility in certain hybrids or genetic instability problems. In spite of these problems, polyploidy is still a critical tool in contemporary plant breeding, especially in creating new cultivars and enhanced agricultural productivity.
For CSS Competitive Exam aspirants, a good grasp of polyploidy—its types, causes, and uses—is important to answer questions on plant genetics, biotechnology, and agricultural science. The MCQs in this article will check your knowledge of polyploidy and its significance in the development of plant breeding and genetic improvement techniques.
